The human ear has a limited range of hearing. The maximum range of human hearing includes sound frequencies from about 15 to about 18,000 waves, or cycles, per second. The general range of hearing for young people is 20 Hz to 20 kHz. As you age the hearing range depletes further as the hair cell’s hair-like stereocilia may get damaged or broken. If enough of them are damaged, hearing loss results which is often irreversable.

Noise induced hearing loss occurs at more than 80 decibels for human beings. The louder the noise the more instant the damage. A rough estimate of loudness of the Big Bang that created us all is between 100 dB to 120 dB. Naturally no human ear will survive actually hearing this sound. Still this is not the loudest noise known to humans.

Apparently the explosion of the Tunguska Meteor which occurred in the year 1908 was recorded at 300 dB making it the loudest sound that human beings know of. Of course there is always the possibility that somewhere out in space there is a planet collision, supernovae explosions or black hole creations which may be louder than this, but that is subject of a different space exploration science project for someone to tackle in the future.

Ask any pet owner and they will swear that their pet can hear and understand everything that they say, not to mention that they respond even though hampered by lack of speech. There are some who will go so far as to say that their dogs can even anticipate what the owners are going to do even before the actual actions take place. So just how intelligent is your pet dog?

The researchers at the University of Sussex decided to find out. The study which was conducted last year shows good evidence that dogs can identify a number or human speech subtleties. The tone of the voice is definitely what they respond to more than the actual words if someone is merely speaking.

However if their owner is actually giving them commands, they listen for the exact words. They will respond to an exact command even if it id delivered in an unfamiliar accent. What’s more, the pet dogs were even able to distinguish between correct commands as opposed to ones with jumbled syllables.

For instance “Come on, then” got a response while “Thumb on, Ken” did not. So you know that the dogs could actually figure out some of the words themselves and not just go with the tone. All in all this science project proved what dog owners around the world already know, dogs are very intelligent beings!

There is nothing quite as disgusting as the sludge that flows through the many sewage drains of our mighty cities. The complex drainage system that literally takes the crap out of your house has a far from pleasing end result. There have been no productive uses of this sewage sludge till now.

At the Universiti Putra Malaysia, researchers are coming up with a way to use dried sewage sludge as an alternative cement material for concrete. As the volume of sludge increases and the environmental laws get more strict about legal ways to dispose of it, this science experiment could actually have far reaching consequences.

What they did is to first produce domestic waste sludge powder or DWSP  by taking regular sludge and then dried it. This was later powdered and mixed with cement at different ratios for different consistencies. 3, 5, 7, 10 and 15% mixtures were made and then compared to regular cement in terms of their compressive strength, water absorption, water permeability and rapid chloride ion penetration.

While more detailed studies and analysis will be required, the researchers have said that there is great potential in the study conducted. DWSP can be used as a partial cement replacement in the future as long as some more science projects figure out just how to use it.

Minerals are defined by their unique combination of chemical composition and crystal structure. Rather like the words in a book some minerals are commonly found while others are rare and define the vocabulary present in a book. A mineral species is only likely to be found in one location about 22 percent of the time. Finding the same mineral species in more than five locations is an extremely rare event.

This is why certain areas are easily mined for a specific mineral while you will have no trace of the same mineral in certain other areas. Rare minerals define our planet’s mineralogical diversity as per Robert Hazen. Hazen has been studying the diversity of minerals in the soil and has analysed large chunks of the Earth’s surface. He believes that thousands of plausible rare minerals either still await discovery or have been buried and lost in Earth’s violent tectonic plate rebalances.

Hazen and his colleagues predicted that nearly 35 percent of sodium minerals remain undiscovered, because more than half of them are white, poorly crystallized, or water soluble. By contrast, fewer than 20 percent of copper, magnesium, and copper minerals have not been discovered. Needless to say the results of this science study will keep mineralogists busy for decades!

That the Earth is unique in our knowledge that it is the only planet with life on it is old news. Now new research at the Carnegie Institute says that the Earth is unique even in its mineralogy. That nowhere in the cosmos is there as much mineral diversity as there is on Earth. With more than fifteen hundred undiscovered minerals and nearly five thousand already known, the diversity of Earth’s minerals is unlikely to be duplicated anywhere in the solar system or even the universe.

Robert Hazen, team leader of the study developed a theory about a decade ago that the large number of minerals found on the planet correspond to the rise of life. That the minerals have been produced either as a direct consequence of biological activity, or have been indirectly influenced by it. Bacterial photosynthesis which increased oxygen concentration in our atmosphere  more than 2.4 billion years ago, has been a primary catalyst for this mineral diversity.

Needless to say, that if biological activity is related to mineral diversity, then a planet with no life is likely to have far less mineral diversity. This means that the scientific study postulates that in the absence of life, no other planet will have the same rich mineralogy as Earth.

At Carnegie Institute Robert Hazen has been working on the unique mineralogy of the planet Earth for more than a decade.  Hazen says that minerals follow the same kind of frequency of distribution as words in a book. For example, the most-used words in a book are extremely common such as ‘and,’ ‘the,’ and ‘a.’ Rare words define the diversity of a book’s vocabulary. The same is true for minerals on Earth, Hazen says.

Hazen also feels that the vast diversity of minerals found on Earth is because of the vast diversity of biological activity that living things perform on Earth. Hazen’s team applied the biological concepts of chance and necessity to mineral evolution and found that